Process and apparatus for modifying and determining the optimum volume of the operating reaction chamber in ovens employed for the production of acetylene from hydrocarbons



Nov. 30, 1965 w. BILL] 3,220,803

PROCESS AND APPARATUS FOR MODIFYING AND DETERMINING THE OPTIMUM VOLUME OF THE OPERATING REACTION CHAMBER IN ovENs EMPLOYED FOR THE PRODUCTION OF ACETYLENE FROM HYDROCARBONS Filed July 6, 1960 United States Patent Italy Filed July 6, 1960, Ser. No. 41,197 Claims priority, application Italy, July 8, 1959, 11,370/59 4 Claims. ((31. 23-277) This invention relates to an improvement in a process and apparatus for making acetylene, primarily, and also olefines such as ethylene, and also carbon, by the partial combustion by hydrocarbons. The emphasis herein is on increasing the yield of acetylene.

The invention is an improvement in the processes described in the co-assigned copending US. applications of Giacomo Fauser, Serial No. 860,794, filed December 21, 1959, now abandoned; Serial No. 814,146, filed May 19, 1959, now US. Patent No. 3,140,323; and Serial No. 757,740, filed August 28, 1958.

Acetylene is produced, in continuous processes, by partial combustion of hydrocarbons with an oxygen-containing substance or gas. The technique involves either injecting the hydrocarbons into a flame obtained by combustion of other hydrocarbons, or in mixing the hydrocarbon with the oxygen-containing substance, the latter being separately pre-heated, and in then igniting the mixture. In both cases, the reaction is halted by cooling with a jet of water, after the gases have remained in the reaction chamber a few hundredths of a second.

It is known that this time depends both upon the type i of hydrocarbon to be submitted to cracking and upon the oxygen content of the substance supporting the combustion, as well as upon the pre-heating temperature and the pressure under which reaction takes place.

Moreover it is known that, for a certain flow of the hydrocarbon to be processed, this time depends upon the distance of the burning block from the area where the rapid cooling occurs, that is, once the purity of the combustion supporting substance, the pre-heating temperature, the pressure and the volume of the reaction chamber are established, and therefore also once the section of the chamber is established. This volume is determined, in commercial operation, by conducting a series of subsequent running tests, in accordance with which, after disassembling the oven, the necessary modifications are made in the reaction chamber. The reaction chamber, when set up, has thus an optimum value only for a given quantity and quality of hydrocarbon, and for a given operating pressure and purity of the combustion supporting substance. This causes a limitation in the flexibility of the operating conditions of the oven, and a laborious investigation to determine the best sizes of the reaction chamber, for each set of standard conditions.

The principal object of this invention is therefore improvement of the process and apparatus employed for producing acetylene by partial combustion of hydrocarbons.

Another object is to obtain such improvement by varying the volume of the reaction chamber, even during the very operation of the process, by shifting the burning block or plate, in order to rapidly reach an optimum volume for each predetermined operating condition. Such condition is a composite of type and flow volume or velocity of hydrocarbon fed, the operating pressure, and the pre-heating temperature of the gases, as Well as others herein made obvious to persons skilled in the art.

The shifting of the burning block or plate in respect to the fixed frame of the oven can comprise a simple translation, and preferably utilizes devices which do not adversely atfect the gas tightness. It is apparent that the process carried out according to the present invention permits a given oven to be rapidly adapted, even during operation, to various types of feeding hydrocarbons, such as methane, ethane, and light gasolines containing various percentages of hydrogen. This gives the ovens the characteristic of outstanding flexibility, which has great practical importance.

The accompanying drawing illustrates in FIG. 1 a preferred embodiment of an apparatus used to carry out the processes described above, and in the examples below.

FIG. 2 shows a detail of FIG. 1.

Oxygen-containing gas enters at O and at A is the hydrocarbon inlet, 1 is the burning block, and 2 designates the reaction chamber. At 3 is the region where the combustion flame or the reaction is extinguished or stopped by injecting water. The numerals 4 designate the stuffing-boxes, 5 the supporting structure, 6 threaded shafts, 7 the clutches of the threaded shafts, 8 the burning block bolts, and 9 designates the shaft sprocket wheels. At 10 is the shaft and worm screw for rotating the two sprocket gears 9.

The burning block is provided with the usual burner outlet grid 81. The block 80 is mounted upon the threaded standards 6 by means of the screw-threaded members 8 that mate with 6. When the standards are turned, the block 80 is raised or lowered along the gas inlet pipe 82.

In the embodiment illustrated, the volume of the reaction zone 2 is substantially defined between the burner head 81 and the lower edge of the Wall 20 of the reaction zone 2, but in practice may extend downwardly to the actual point of extinguishment of the flame or chilling of the reaction gases by the sprays of water indicated in the drawing. That point is designated 3 in the drawing.

The synchronous rotations of the threaded shafts 6, obtained by rotating the shaft 10 and gears 9, allows the burning block 80 to be moved towards or away from the zone of rapid cooling, during the operation of the oven, thus varying the length of the reaction chamber 2. The gas tightness of the latter is maintained by the stuflingbox 4.

It is understood that the following examples and the drawing illustrate preferred embodiments of the invention, and are not intended to limit its scope.

The procedure employed in the manufacture of acetylene and olefines from liquid or gaseous hydrocarbons comprises carrying out a partial combustion with oxygen at a temperature preferably higher than 1500 C., and then cooling or quenching the combustion products as quickly as possible, in order to prevent dissocation of the acetylene. The pressure is generally close to atmospheric, but as revealed in Serial No. 860,794, application of a pressure of two to six atmospheres has marked advantages. The quenching is usually carried out by spraying Water into the flame or exit gases. This is exemplified here. However, as revealed in Serial No. 860,794, it is advantageous to carry out a preliminary stage partial quench, to about 750-800 C., by injecting hydrocarbons to be cracked before the quenching with water, and in this case too marked advantages are obtained by making provision for varying, during the very operation of the process, the volume of the reaction chamber, before the quenching with hydrocarbons.

The natural gas, or other hydrocarbon, and oxygen can be separately pre-heated to about 520 C., or below, or together.

The term Nm means cubic meters of the gas recalculated at 0 C. and 760 mm. of mercury.

Whether the volume of the reaction zone is to be increased or decreased during the reaction depends upon whether it is the yield of acetylene that is to be increased, or that of other hydrocarbons such as ethylene, or of carbon. Such gas yields are readily determined by automatic and standard gas testing apparatus, while the process is in operation. In the specific examples given below the volume of the reaction zone is increased.

Example 1 In an oven having a normal capacity of 2,000 Nm per hour of natural gas (98% CH the burning block was shifted in respect to the extinguishing zone 3 during the operation of the oven, while maintaining standard and conventional temperature and pressure operating conditions, but reducing, by about the volume of the reaction chamber in respect to what it Was before the application of the device. A 1.8% increase of the yield in C H per kg. of hydrocarbon is obtained.

In this example the volume of the reaction chamber 2 is increased by 5%.

Example 2 This example is carried outv in the same oven. By shifting the burning block in respect to the extinguishing zone, during the operation, the C H yield was maintained at maximum value, in a flow range of 500 to 2,500 Nm /H of hydrocarbon, while increasing correspondingly the volume of the reaction chamber at a 126.3 ratio. This is a volume increase ratio.

Example 3 This example is also carried out in the same oven, but with a flow 1,850 Nm /H of natural gas, and With lowering of the pre-heating temperature of the natural gas and oxygen from 520 to 280 C., and an increase of 8.5% in the quantity of oxygen. As a result, there was a 25 .4% decrease in the C H yield per kg. of hydrocarbon.

In a second time reaction, in which the operating conditions have not changed except for an increase in the volume of the chamber by 18.2%, it was possible to increase the C H yield up to a value only 5.3% lower than that obtained when the pre-heating was carried out at 520 C.

Example 4 The oven employed had a nominal capacity of 800 kg./ H of light gasoline. The shifting of the burner block 80, which comprises the generator of the primary flame and the injection zone of the gasoline to be heated, in respect to the blowing-out zone as explained above, which shifting was carried out during the operation of the oven, resulted in maintenance of the acetylene yield at maximum value, in a flow range of the hydrocarbon of from 200 kg. to 800 kg./H, while increasing, correspondingly, the volume of the chamber located under the injection zone of the gasoline in a 1:55 ratio.

Example 5 This example .is carried out in the oven of Example 4. Upon operating with a flow of 500 kg. per hour of gasoline, a decrease of about 4.5% of the acetylene yield was noted upon changing from a light paraffinic gasoline characterized by an 85% by weight content of carbon and 15% by weight of hydrogen to another type of light paraffinic gasoline characterized by an 84% by weight content of carbon and 16% by weight of hydrogen, while maintaining all other standard operating conditions unvaried. In a second time, when operating with the second type of gasoline, and leaving all operating conditions unvaried except increasing the volume of the reaction chamber by 8.1%, it was possible to increase the acetylene yield up to the same value obtained when using the first type of gasoline.

I claim:

1. An apparatus for partial combustion of a hydrocarbon with a free oxygen-containing gas to make an unsaturated hydrocarbon, comprising a structure providing a reaction chamber, a mixing chamber upstream of said reaction chamber, a burner structure with a grid communicating with said mixing chamber and said reaction chamber, said burner structure axially movable within the reaction chamber, means for movably mounting the burner structure, gas sealing means between the burner structure and the reaction chamber structure, means for moving the burner structure axially in either direction within said reaction chamber, the burner structure and reaction chamber structure telescoping at least in part, the burner having outside wall surface closely adjacent to inner wall surface of the reaction chamber, so that movement of the burner within the reaction chamber substantially controls the volume of the reaction chamber and the mixing chamber, and conduit means for introducing a reaction quenching fluid at the outlet region of the reaction chamber to delimit the extent of the effective reaction zone.

2. An apparatus for carrying out a controlled partial combustion of a hydrocarbon fluid, comprising a reaction chamber structure, a mixing chamber structure upstream of said reaction chamber structure, and a burner block structure between said mixing chamber structure and said. reaction chamber structure, the mixing chamber structure having provision for intake of the hydrocarbon fluid and free oxygen-containing gas, the burner block structure and reaction chamber structure being mounted for axial displacement relative to each other, the burner block structure having a burner head with a grid in telescoping engagement with the inner wall of the reaction chamber, the burner block structure having outside wall surface closely adjacent to the inner wall surface of the reaction chamber, drive means for carrying out said displacement operable while the combustion is going on, means for introducing quenching fluid to halt the combustion at the outlet region of the combustion chamber.

3. An apparatus for production of acetylene by a controlled partial combustion of a hydrocarbon fluid in a reaction chamber, and for halting the reaction by quenching the resulting hot reaction gases after the gases have been in the reaction chamber for a few hundredths of a second, to minimize dissociation of the acetylene, comprising a reaction chamber structure, a mixing chamber structure upstream of said reaction chamber structure, and a burner block structure with a grid between said mixing chamber structure and said reaction chamber structure, the mixing chamber structure having provision for intake of the hydrocarbon fluid and free oxygen-containing gas, the burner block structure and reaction chamber structure being mounted for displacement relative to each other, drive means for carrying out said displacement operable while the combustion is going on, means for introducing quenching fluid to halt the combustion at the outlet region of the combustion chamber, said burner block structure and reaction chamber structure at least in part closely telescoping, one Within the other, so that said rela tive displacement modifies the volume of the reaction chamber-and the mixing chamber.

4. An apparatus for making acetylene by partial combustion of a hydrocarbon with a free oxygen-containing gas, comprising a structure providing a reaction chamber, a mixing chamber upstream of said reaction chamber, a burner structure with a grid communicating with said mixing chamber and said reaction chamber, said burner structure axially movable within the reaction chamber, conduit means for introducing the hydrocarbon and the oxygen-containing gas into the burner structure, the burner structure extending transversely across the reaction chamber, the burner block structure having outside Wall surface closely adjacent to the inner wall surface of the reaction chamber, means for movably mounting the burner structure, gas sealing means between the burner structure and the reaction chamber structure, means for moving the burner structure and outlet member in either axial direction Within said reaction chamber, so as to modify the volume of the reaction chamber and the mixing chamber, and conduit means for introducing a reaction quenching fluid at the outlet region of the reaction chamber to delimit the effective extent of the reaction chamber, so as to minimize dissociation of the acetylene.

References Cited by the Examiner UNITED STATES PATENTS 1,965,771 7/1934 Groll et a1. 260-170 2,353,505 7/ 1944 Scheineman 23-288.3 X 2,418,712 4/1947 Heymann 158-28 X 6 Hartwig et a1 23284 Cunningham 260-679 Lehner et a1. 23277 Hale 23277 Minarik 260-679 OTHER REFERENCES Patton et a1.: Petroleum Refiner, November 1958, vol. 37, No. 11, pp. 180186.

PAUL M. COUGHLAN, Primary Examiner.

ALPHONSO D. SULLIVAN, MILTON STERMAN,

Examiners. 

1. AN APPARATUS FOR PARTIAL COMBUSTION OF A HYDROCARBON WITH A FREE OXYGEN-CONTAINING GAS TO MAKE AN UNSATURATED HYDROCARBON, COMPRISING A STRUCTURE PROVIDING A REACTION CHAMBER, A MIXING CHAMBER UPSTREAM OF SAID REACTION CHAMBER, A BURNER STRUCTURE WITH A GRID COMMUNICATING WITH SAID MIXING CHAMBER AND SIAD REACTION CHAMBER, SAID BURNER STRUCTURE AXIALLY MOVABLE WITHIN THE REACTION CHAMBER, MEANS FOR MOVABLY MOUNTING THE BURNER STRUCTURE, GAS SEALING MEANS BETWEEN THE BURNER STRUCTURE AND THE REACTION CHAMBER STRUCTURE, MEANS FOR MOVING THE BURNER STRUCTURE AXIALLY IN EITHER DIRECTION WITHIN SAID REACTION CHAMBER, THE BURNER STRUCTURE AND REACTION CHAMBER STRUCTURE TELESCOPING AT LEAST IN PART, THE BURNER HAVING OUTSIDE WALL SURFACE CLOSELY ADJACENT TO INNER WALL SURFACE OF THE REACTION CHAMBER, SO THAT MOVEMENT OF THE BURNER WITHIN THE REACTION CHAMBER SUBSTANTIALLY CONTROLS THE VOLUME OF THE REACTION CHAMBER AND THE MIXING CHAMBER, AND CONDUIT MEANS FOR INTRODUCING A REACTION QUENCHING FLUID AT THE OUTLET REGION OF THE REACTION CHAMBER TO DELIMIT THE EXTENT OF THE EFFECTIVE REACTION ZONE. 